ddi_mem_alloc(9F) manual page
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ddi_mem_alloc, ddi_mem_free - allocate and free sequentially accessed
memory
#include <sys/ddi.h>
#include <sys/sunddi.h>
int ddi_mem_alloc(dev_info_t *dip, ddi_dma_lim_t *limits,
u_int length, u_int flags, caddr_t *kaddrp, u_int *real_length);
void
ddi_mem_free(caddr_t kaddr);
Solaris DDI specific (Solaris
DDI).
- dip
- A pointer to the device’s dev_info structure.
- limits
- A pointer to a DMA
limits structure for this device (see ddi_dma_lim_sparc(9S)
or ddi_dma_lim_x86(9S)
). If this pointer is NULL
, a default set of DMA
limits
is assumed.
- length
- The length in bytes of the desired allocation.
- flags
- The
possible flags 1 and 0 are taken to mean, respectively, wait until memory
is available, or do not wait.
- kaddrp
- On a successful return, *kaddrp points
to the allocated memory.
- real_length
- The length in bytes that was allocated.
Alignment and padding requirements may cause ddi_mem_alloc() to allocate
more memory than requested in length.
- kaddr
- The memory returned
from a successful call to ddi_mem_alloc().
ddi_mem_alloc()
allocates memory for DMA
transfers and should be used if the device is
performing sequential, unidirectional, block-sized and block-aligned transfers
to or from memory. This type of access is commonly known as streaming access.
The allocation will obey the alignment and padding constraints as specified
by the limits argument and other limits imposed by the system.
Note that
you must still use DMA
resource allocation functions (see ddi_dma_setup(9F)
)
to establish DMA
resources for the memory allocated using ddi_mem_alloc().
ddi_mem_alloc() returns the actual size of the allocated memory object.
Because of padding and alignment requirements, the actual size might be
larger than the requested size. ddi_dma_setup(9F)
requires the actual length.
In order to make the view of a memory object shared between a CPU
and a
DMA
device consistent, explicit synchronization steps using ddi_dma_sync(9F)
or ddi_dma_free(9F)
are required.
ddi_mem_free() frees up memory allocated
by ddi_mem_alloc().
ddi_mem_alloc() returns:
- DDI_SUCCESS
- Memory
successfully allocated.
- DDI_FAILURE
- Allocation failed.
ddi_mem_alloc()
can be called from user or interrupt context, except when flags is set
to 1, in which case it can be called from user context only.
ddi_dma_free(9F)
,
ddi_dma_setup(9F)
, ddi_dma_sync(9F)
, ddi_iopb_alloc(9F)
, ddi_dma_lim_sparc(9S)
,
ddi_dma_lim_x86(9S)
, ddi_dma_req(9S)
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